The temperature of the PV module, which is part of the SPI with a concentration of solar energy less than 10 000 W/m2, in the absence of artificial PV module cooling, can accurately be described by the formula:Tm=t+1,25G(TNOCT−20)   (1),
where t— ambient temperature (° C.), TNOCT— normal operating temperature of PV module (° C.), G— solar concentration ratio.
There are known concentrator SPI based on bifacial PV modules with solar energy concentrator built on flat reflecting plates: RU Patent No2406043 and Super TRAXLE 5× concentrator (http://www.solar-trackers.com/). In these SPIs, bifacial PV modules are installed in the focal plane of a flat concentrator, from which it receives uniform sunlight with a concentration ratio G≥3. Heat removal from the PV module is carried out by natural cooling.
The disadvantage of these SPIs is a significant decrease in the output power due to strong heating of the PV module. According to the formula (1), the design temperature Tm at an ambient temperature of +30° C. will be about 100° C. As a result, there will be a decrease of power output by more than 30% and exceed the maximum guaranteed operating temperature in +85° C. for the standard PV modules.
A known SunPower C7 Tracker is a concentrator SPI with the value of solar concentration ratio of G=7 (http://us.sunpower.com/). To remove the heat on the back side of the solar PV cells, a copper foil is soldered in a form of collector lanes, and the copper foil is placed on a metal radiator.
The disadvantages of C7 Tracker are:                lower power drop from ambient temperature than in the previous two SPIs, but still insufficient to provide high parameters at ambient temperature above +40° C.;        bifacial PV modules operate as single-sided ones, which reduces the total efficiency;        mirror concentrators have cylindrical shape and are directed bulge downwards, which leads to an intense accumulation of dust and moisture in them.        
Russian Patent 2,382,953 discloses a combined solar power station. Bifacial PV cells are set in a closed housing with transparent windows, filled with coolant. This closed housing fits in a second housing, in which the heat carrier circulates through the heat transfer loop. PV cells receive the sunlight on both sides from the concentrator. The heat from the surface of the PV cells is taken away by the coolant and proceeds, in the circulation circuit, to the consumer.
The SPI disclosed in RU 2,382,953 has the following disadvantages:                Using of parabolic concentrator leads to the need to have the PV cells of small size, so that they are in the focus of a parabolic cylinder, otherwise, the efficiency of the installation is drastically reduced.        There is a contradiction in the design of the SPI as disclosed in RU 2382953. In order to increase the efficiency of operation, the temperature of the PV cells should be as low as possible and not exceed the boundary upper operating temperature of PC cells. For effective operation of the heat circuit, it is desirable to have PV cells temperature as high as possible.        The design of the SPI disclosed in RU 2,382,953 is very complex and expensive.        